Conventional packaged microelectronic devices are manufactured for specific performance characteristics required for use in a wide range of electronic equipment. Packaged microelectronic devices typically include a die with integrated circuitry, a casing encapsulating the die, and an array of external contacts or terminals. Packaged microelectronic devices have an outer shape that defines a package profile. The external contacts can include (a) contacts that protrude from the device (e.g., pin-like leads, ball-pads, solder balls, or bumps of a ball-grid array (BGA), etc.) or (b) non-protruding, generally planar contacts or pads (e.g., land grid arrays (LGA), leadless chip carriers, quad flat-pack no-lead packages, etc.) The external contacts are arranged in a selected pattern and configured to be electrically and physically coupled to other external devices. Different types of packaged devices with different circuitry can have the same outer profile but a different arrangement of external contacts.
After the dies are packaged, the devices are generally tested and marked in several post-production batch processes. Burn-in testing is one such post-production process for detecting whether any of the devices are likely to fail. Burn-in testing is performed before shipping packaged devices to customers or installing packaged devices in electronic equipment. Burn-in testing of packaged devices typically involves applying specified electrical biases and/or signals to the external contacts of the devices in a controlled temperature environment. The packaged devices are generally tested under more severe conditions and/or under more rigorous performance parameters than they are likely to experience during normal operation.
FIG. 1, for example, is a schematic side cross-sectional view of a portion of a conventional testing system 10 including a test bed 20 carrying a packaged microelectronic device 12. The test bed 20 includes a test socket 22 having lead-in surfaces 24 and side surfaces 26 that define a recess 28 for receiving the device 12. A shelf 30 in the recess 28 supports an outer perimeter region of the device 12, and external contacts 14 on the device 12 are positioned within an opening 32 defined by the shelf 30. A tester interface 40 that includes a plurality of test contacts 42 is positioned below the test bed 20 with the test contacts 42 positioned to contact corresponding external contacts 14.
The test contacts 42 can be selected based on the particular configuration of the external contacts 14. For example, if the external contacts 14 include protruding elements such as solder balls, the test contacts 42 can include clamps or pincers configured to pinch or hold the protruding contacts 14. On the other hand, if the external contacts 14 include generally planar elements, such as an LGA, the test contacts 42 can include vertically biased contacts configured to engage the corresponding non-protruding contacts 14. The test socket 22 is movable relative to the tester interface 40 so that the test contacts 42 can engage and apply electrical signals to corresponding external contacts 14 for testing the device 12. Although only a single test socket 22 and device 12 are shown in FIG. 1, it will be appreciated that the system 10 can include a number of test sockets 22 for testing a number of devices 12 either individually or in a batch process.
One problem with conventional testing systems is that it is difficult to perform burn-in tests for runs of devices having different configurations. For example, the arrangement of external contacts on one batch of devices to be tested may be different than the arrangement of external contacts on another batch of devices and, accordingly, the external contacts of the individual devices may not be aligned with corresponding test contacts. In the testing system 10 of FIG. 1, for example, the arrangement of test contacts 42 may not be the same as the arrangement of external contacts 14 on the device 12. As such, the external contacts 14 may not be properly aligned with the test contacts 42 and the device 12 may fail the test even though the device 12 otherwise functions properly. Furthermore, if one or more portions of the device 12 are not populated with external contacts 14, the test contact(s) 42 aligned with that portion of the device 12 can scratch, impinge, pierce, and/or otherwise damage the device 12. In some cases, for example, the unmatched test contacts 42 can puncture the soft, protective coating on an external surface of the device 12 and damage or short out the device's internal circuitry.
One approach to addressing this drawback is to reconfigure the testing system to accommodate the different arrangements of external contacts on each device to be tested. In the testing system 10 of FIG. 1, for example, the system can be reconfigured by replacing the test sockets 22 with different test sockets configured for use with a particular batch of devices. Further, in some cases the tester interface 40 can be reconfigured by adding or eliminating test contacts 42 such that the number and arrangement of test contacts 42 is precisely coordinated with the arrangement of external contacts 14 on the device 12. In a typical large scale manufacturing process for microelectronic devices, however, replacing each of the test sockets 22 and/or reconfiguring the test contacts 42 to test devices having different arrangements of external contacts typically involves reconfiguring a large number of system components. This process is accordingly extremely labor-intensive, time-consuming, and expensive because it not only requires many hours of skilled labor, but it also results in costly downtime for the testing systems. Accordingly, there is a need for improved systems and methods for testing microelectronic devices.